248 DIY Science: Illustrated Guide to Home Chemistry Experiments
FIGURE 14-1:
Measuring gas volume as compressed by a measured mass
LABORATORY 1 4.1:
oBSERvE THE voLUmE-pRESSURE RELATIoNSHIp of GASES
(Boyle’s Law)
Boyle’s Law states that, at constant
temperature, the volume of a gas is inversely
proportional to its pressure. In this laboratory
session, we’ll verify Boyle’s Law experimentally,
using the setup shown in Figure 14-1. (You
can buy a ready-made Boyle’s Law apparatus
from Home Science Tools or other vendors,
but $10 or $12 is a pretty high price to pay for
a disposable syringe and two blocks of wood.)
The apparatus shown in Figure 14-1 uses only
standard lab equipment, and is at least as
accurate as a ready-made apparatus.
RIREEqU d EqUIpmENT ANd SUppLIES£ goggles, gloves, and protective clothing£ balance and weighing cup£ caliper£ barometer (optional)£ ring stand£ burette or utility clamp (to fit syringe)£ 4 " (100 mm) support ring£ plastic syringe, 10 mL to 50 mL, graduated, with cap£ mineral oil or petroleum jelly (1 drop)£ plastic cup (to fit support ring)£ lead shot (10 pounds or 5 kilograms)SBSTITUTIU oNS ANd modIfICATIoNS- If you do not have a caliper, you may substitute a
metric ruler with millimeter markings, although you
will sacrifice significant accuracy. - If you do not have a barometer, you may use the
barometric pressure broadcast by a local TV or radio
station or the Weather Channel web site for your zip
code, but see the note on the next page. - You may substitute any sturdy lightweight container of
similar size for the plastic cup, including an aluminum
beverage can with the top removed. The container
should fit loosely within the support ring; not closely
enough to bind, but closely enough to keep the
container centered over the syringe plunger when
mass is added to the container. - You may substitute any dense material for the lead
shot, such as old wheel weights, fishing sinkers, spools
of solder, and so on. Ideally, the material should be
dense enough to allow the container to hold at least
3 kilograms of mass. Syringes with large bores require
more mass for equivalent compression.